1. Field of the Invention
The present invention relates to an image data processing method and an imaging apparatus for sharpening an image that is defocused due to being captured out of focus by an imaging device such as a digital camera.
2. Description of the Related Art
There exist technologies proposed to sharpen a defocused image (also known as blurred image) that are produced when a photograph is captured out of focus. For example, in Patent Document 1, a method is proposed to correct, with high accuracy, images that are heterogeneously blurred both rotationally and with parallel displacement. This method corrects the blurring by estimating the blur vector of each pixel of an image and performing interpolated calculation on each pixel according to the blur vector of the pixel location. The blur vector is estimated using a coordinate transformation matrix for the rotational and horizontal movement occurred by camera shake.
In Patent Document 2, the blur function (point spread function (PSF)) is set using any one or more of the basic functionality parameters and the capture parameters which can be used to improve focus of each pixel in a 3 dimensional image data procured by capturing the internal structure of the photo subject under given capture parameters. And these settings of the PSF are used for the blur correction process. From the captured 3 dimensional image data, the blurs caused by the basic functionality and capture conditions are reduced for each pixel by reducing the blur component on the pixel level, and then the image processing using the 3 dimensional image data sharpens the image and improves image quality.
In Patent Document 3, in order to sharpen an image that has both focused areas and out of focus (defocused) areas, all pixels of target image is considered to be target pixels, and the estimated blur circle shows the influence to the color information of the pixels surrounding the target pixels. Furthermore, this estimated blur circle is used for the inverse PSF, which corrects the image so that the color information of the target pixels is not influenced by the surrounding pixels.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-298300
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2005-58760
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2005-63000